在揭示军用飞机发展本质的基础上，提出了统领飞机发展的顶层综合特性———可持续发展性，给出 了其定义和度量方式；进一步指出用可持续发展指数作为可发展性的表征参数能够更有效地进行评估，并在此 基础上建立了可发展性的综合权衡模型。最后，将可发展性应用到某型歼击机改进方案的评估中。实例表明， 可发展性是迄今为止最为合理的军用飞机顶层综合特性，可有效地使军用飞机发展纳入科学的发展轨道。

The top level integrated property,sustainable developability(SD),which can guide the development of aircrafts,is put forward based on the discovery of the essence in the development of military aircrafts.The definition and metrics of SD are given.The sustainable developability index,which can estimate SD effectively,is formulated to characterize SD.Furthermore,an integrated tradeoff model of SD is established.At last,the application in the modification project estimation of certain type aircraft demonstrates the rationality and effectiveness of SD.